This invention relates to a batch type raw material mixing method used to obtain a viscous material by agitate-mixing a plurality of kinds of raw materials of different properties, and an apparatus therefor, and more particularly to a batch type raw material mixing method capable of reducing the agitate-mixing time and energy consumption and thereby improving a mixing efficiency, and an apparatus therefor.
For example, in order to manufacture a viscous material, such as a bonding agent by a batch type method, a plurality of kinds of raw materials of different properties are placed in a cylindrical container, and agitate-mixed by rotating agitating blades provided in the container. Owing to this agitate-mixing operation, the raw materials react on one another, and a viscous material can be obtained.
The conventional batch type methods in which raw materials are agitate-mixed in this manner include a method in which raw materials are agitate-mixed by rotating agitating blades at a constant rotational speed for a predetermined period of time, a method in which raw materials are agitate-mixed at a predetermined rotational speed as the agitation time is changed every time the raw materials are charged into a container, and a method in which raw materials are agitate-mixed at a different rotational speed for a different period of agitation time every time the raw materials are charged into a container.
In order to obtain a mixture having an object viscosity as soon as possible, the shape, size and rotational speed of the agitating blades are determined in accordance with the properties of the materials to be processed, or baffle plates are fixed to the inner surface of the cylindrical container, whereby the agitate-mixing effect thereof is improved.
Trying to improve the agitate-mixing effect by selectively determining the shape and size of the agitating blades in accordance with the properties of raw materials to be processed may not give rise to troubles when the same viscous mixture is manufactured in every batch. However, an attempt to obtain viscous materials, the properties of which are different in different batches, in the same equipment does not ensure an expected high agitate-mixing effect.
When a cylindrical container provided with baffle plates on the inner surface thereof is used, a mixed viscous material resides on the corner portions of the baffle plates, so that the discharging of the residual viscous material and the cleaning of the interior of the container become troublesome. Furthermore, there is the possibility that a dead zone occurs in which the raw material charged into a portion in the vicinity of a baffle plate is not satisfactorily agitated to reside therein.
A method in which raw materials are agitate-mixed by rotating agitating blades forward and backward alternately so as to improve the agitate-mixing effect has also been proposed. However, in this method, a time zone in which a flow of materials being mixed is completely stopped due to the switching of forward rotation of the agitating blades to backward rotation thereof, and vice versa occurs. Therefore, the viscous materials processed are limited, and this method cannot be suitably used for the production of all kinds of mixtures. Moreover, the energy efficiency is low.